Controllable voltage-signal generation circuitry, including: a plurality of segment nodes connected together in series, each adjacent pair of segment nodes connected together via a corresponding coupling capacitor, an end one of the segment nodes serving as an output node; for each of the segment nodes, at least one segment capacitor having a first terminal connected to that segment node and a second terminal connected to a corresponding switch; and switch control circuitry, wherein: each switch is operable to connect the second terminal to one reference voltage source and then instead to another reference voltage source, to apply a voltage change at the second terminal; the reference voltage sources and switches configured such that for each segment node the same voltage change in magnitude is applied by each switch, and such that the voltage change is different in magnitude from the voltage change applied by each switch of another segment node.